Add Xen paused state as a Ganeti running state

The QA test 'TestClusterBurnin' pauses instances and the Xen state
domain 'paused' was not being handled properly by Ganeti because it
was not being classified as either a running or shutdown state.  This
patch adds the 'paused' state to the set of running states by
extending the function 'ganeti.hypervisor.hv_xen._IsInstanceRunning'
with the corresponding Xen state string '--p---'.

This fixes the QA test 'TestClusterBurnin'.
Signed-off-by: Jose A. Lopes <jabolopes@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>

lib/hypervisor/hv_xen.py

@@ -168,9 +168,14 @@ def _GetAllInstanceList(fn, include_node, _timeout=5):
   return _ParseInstanceList(lines, include_node)
 
 
+# Determine whether an instance is running
+#
+# An instance is running if it is in the following Xen states:
+# running, blocked, or paused.
 def _IsInstanceRunning(instance_info):
   return instance_info == "r-----" \
-      or instance_info == "-b----"
+      or instance_info == "-b----" \
+      or instance_info == "--p---"
 
 
 def _IsInstanceShutdown(instance_info):